JP3615372B2 - Infrared thermometer - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an infrared thermometer.
[0002]
[Prior art]
In recent years, with the progress of infrared technology, infrared thermometers are often used.
[0003]
In the infrared thermometer, the intensity of infrared rays generated from the measurement site is detected by an infrared sensor, the ambient temperature is detected by a temperature sensor, and the body temperature is obtained in a short time from the infrared sensor output and the temperature sensor output. For this reason, there is a great advantage that the measurement time is extremely short (for example, about 1 to 2 seconds) compared with a conventional thermometer that has been used conventionally, for example, when measuring the body temperature of an infant or child who is restless Is extremely useful.
[0004]
However, when at least one of the detection time of the signal from the infrared sensor and the detection time of the signal from the temperature sensor has temperature dependence, there is a disadvantage that the measurement time of the body temperature varies, particularly due to different environmental temperatures.
[0005]
[Problems to be solved by the invention]
The objective of this invention is providing the infrared thermometer which can reduce the variation in the measurement time of body temperature.
[0006]
[Means for Solving the Problems]
Such an object is achieved by the present invention described in (1) or (2) below.
[0007]
(1) Provided with a resistor whose resistance value increases as the temperature decreases, the greater the temperature difference between the temperature sensor that detects the environmental temperature and the hot and cold junctions, the greater the level of the signal that is output, Infrared thermometer that detects the intensity of infrared rays emitted from a measurement site, and an infrared thermometer that measures body temperature based on signals from the temperature sensor and the infrared sensor,
A CR oscillation circuit including a resistor of the temperature sensor as a resistor; And detecting the signal from the infrared sensor, the level of the reference signal is decreased from a predetermined value larger than the level of the signal from the infrared sensor, and the reference signal By measuring the time until the level matches the level of the signal from the infrared sensor and obtaining the second time information corresponding to the intensity of infrared rays emitted from the measurement site, the environmental temperature is low As the detection time of the signal from the temperature sensor is longer and the temperature difference between the temperature of the measurement site and the ambient temperature is larger, the infrared sensor Detection time of a signal from the over is configured to be shorter,
An infrared thermometer characterized in that a body temperature is obtained using the first time information and the second time information.
[0008]
(2) The infrared thermometer according to (1), wherein a total time of a detection time of the signal from the temperature sensor and a detection time of the signal from the infrared sensor is constant.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the infrared thermometer of the present invention will be described in detail based on a preferred embodiment shown in the accompanying drawings.
[0014]
1 and 2 are a front view and a side view of an infrared thermometer of the present invention (hereinafter simply referred to as “thermometer”), respectively, and FIG. 3 shows a state in which the probe cover is attached to the probe in the thermometer of the present invention. 1 is a cross-sectional side view schematically showing the internal structure of the thermometer of the present invention, FIG. 5 is a perspective view showing the structure of the temperature measuring unit, and FIG. 6 is the present invention. It is a block diagram which shows the circuit structural example of this thermometer. For convenience of explanation, the upper side of FIGS. 1 and 2 is called “upper”, the lower side is called “lower”, the upper side of FIGS. 3 and 4 is called “tip”, and the lower side is called “base”.
[0015]
As shown in FIGS. 1 to 4, the thermometer 1 of the present invention is an ear thermometer that detects body temperature by measuring the intensity of infrared rays emitted from the ear (the eardrum), and has a casing 21. A power switch 3 and a display unit 5 installed on the front surface of the thermometer body 2, and a measurement switch 4 installed on the upper back of the thermometer body 2.
[0016]
The probe 6 is detachably attached to the thermometer body 2 on the upper front side of the thermometer body 2. As shown in FIG. 3, the support base 7 has a large diameter portion 71 and a small diameter portion 72 on the distal end side thereof. Is formed.
[0017]
On the other hand, the proximal end of the tubular probe 6 has a base 61 that contacts the distal end surface of the large-diameter portion 71, and a female screw 62 that engages with the male screw 74 is formed on the inner surface of the proximal end of the probe 6. Is formed. The probe 6 is supported and fixed to the support base 7 by screwing the male screw 74 and the female screw 62 together.
[0018]
The probe 6 has a shape in which the outer diameter gradually decreases toward the tip, and the tip outer peripheral portion (edge) 63 of the probe 6 is in consideration of safety when inserted into the ear cavity. It has a rounded shape.
[0019]
A light guide (waveguide) 8 that guides infrared rays (heat rays) introduced from the tip of the support base 7 to the infrared sensor 101 of the temperature detection unit 10 is provided upright at the center of the support base 7. The light guide 8 is preferably made of a metal such as copper having good thermal conductivity, and its inner surface is plated with gold.
[0020]
The light guide 8 is covered with a protective sheet 81 so as to cover the opening at the tip. This prevents dust, dust, etc. from entering the light guide 8. The protective sheet 81 has infrared transparency, and examples of the constituent material thereof include the same resin material as the probe cover 11 described later.
[0021]
A ring nut 9 is screwed into the large diameter portion 71 of the support base 7. That is, a female screw 91 is formed on the inner surface of the base end side of the ring nut 9, and the female screw 91 is engaged with the male screw 73 of the large-diameter portion 71 so that the ring nut 9 is supported by the support base 7. Fixed.
[0022]
The ring nut 9 has a tapered portion 92 whose outer diameter gradually decreases from the vicinity of the distal end of the female screw 91 toward the distal end. The inner surface of the tapered portion 92 engages with the body portion 12 of the probe cover 11. An engaging portion 93 is formed.
[0023]
When the probe cover 11 is put on the probe 6, the ring nut 9 is attached, and the body 12 of the probe cover 11 is screwed by rotating in a predetermined direction, the inclined portion 64 of the probe 6 and the engaging portion 93 of the ring nut 9 are engaged. The probe cover 11 is securely fixed to the probe 6.
[0024]
In addition, a flange mounting base or the like is provided around the open end (base end) of the probe cover 11 of the present embodiment, and the probe cover 11 may be fixed by sandwiching the flange or the like between the probe 6 and the ring nut 9. it can.
[0025]
Therefore, it is possible to prevent the probe cover 11 from being displaced from the probe 6 or being easily detached during body temperature measurement or the like. Further, in order to remove the probe cover 11 from the probe 6, the ring nut 9 must be rotated with a considerable force to release the screwing with the large-diameter portion 71, so that the infant accidentally removes the probe cover 11. Inconvenience such as putting in the mouth is also prevented.
[0026]
The tip end surface 94 of the ring nut 9 constitutes a substantially flat surface. When the probe 6 is inserted into the ear cavity, the distal end surface 94 abuts in the vicinity of the ear cavity entrance, and regulates the insertion depth of the probe 6 into the ear cavity to a constant depth. For this reason, measurement under appropriate conditions is always possible, and measurement errors due to variations in the insertion depth into the ear cavity can be prevented, and the depth of the ear is damaged by entering too deeply into the ear cavity of the probe 6. There is no inconvenience.
[0027]
In addition, a plurality of grooves (anti-slip means) 95 exhibiting an anti-slip effect when the ring nut 9 is rotated in the tightening direction or the loosening direction are provided on the outer peripheral surface of the tapered portion 92 of the ring nut 9 in the circumferential direction. It is formed at a predetermined interval. In addition, the same function can be exhibited even if it is not only a recessed part like the groove | channel 95 but a convex part. Further, a high friction material such as rubber may be provided.
[0028]
The probe cover 11 has a shape in which the proximal end is open and the distal end is closed. The probe cover 11 includes a cylindrical body 12 whose outer diameter and inner diameter gradually decrease toward the tip, a film 14 that can transmit infrared rays formed at the tip of the body 12, and an outer periphery of the film 14. The ring-shaped lip portion 15 is formed and protrudes from the film 14 toward the distal end side.
[0029]
And the trunk | drum 12, the film | membrane 14, and the lip | rip part 15 are preferably formed integrally with the resin material. Examples of the resin material include polyolefin such as polyethylene, polypropylene, and ethylene-vinyl acetate copolymer, and polyester such as polyethylene terephthalate and polybutylene terephthalate.
[0030]
In the probe cover 11, since the lip portion 15 exists, the film 14 is lowered from the distal end of the probe cover 11 to the proximal end side by a predetermined distance. As a result, when the probe cover 11 is attached to the probe 6 and inserted into the ear cavity, the membrane 14 touches the inner surface of the ear cavity or the periphery thereof, or when the probe cover 11 is attached to or detached from the probe 6. Since the finger or the like is prevented from being touched and the surface of the film 14 can be kept clean, higher measurement accuracy can be maintained.
[0031]
The inside of the lip portion 15 has a shape that fits into the tip portion of the probe 6. That is, as shown in FIG. 3, when the probe cover 11 is attached to the probe 6, the lip portion 15 is fitted to the outer peripheral portion 63 of the tip of the probe 6. This prevents the tip of the probe cover 11 from being displaced with respect to the probe 6 during insertion into the ear cavity (measurement) or the like, and the membrane 14 is stretched with a constant tension. Since wrinkles and sagging are prevented from occurring, this contributes to improvement in measurement accuracy.
[0032]
Moreover, the tip of the lip portion 15 has a rounded shape. Thus, when inserted into the ear cavity, high safety is ensured without feeling pain or damaging the inner wall of the ear cavity.
[0033]
As shown in FIG. 4, a circuit board 30 is installed in the casing 21. As shown in FIGS. 4 and 6, the circuit board 30 has a temperature measuring unit 10 and a control means 31 including a microcomputer. Amplifying means 32, changeover switch 35, integration circuit 36, comparator 37, reference resistor 38, changeover switch 39, relay circuit 41 and buzzer 42 are mounted. In addition, a power supply unit 40 that houses a battery is installed in the casing 21, and electric power is supplied from the power supply unit 40 to each part of the circuit board 30.
[0034]
The temperature detection unit 10 includes an infrared sensor 101 and a temperature sensor 107.
[0035]
The control unit 31 includes a calculation unit 311, a memory (RAM, ROM, EEPROM) 312, a timer (including an auto power off timer) 313, and a counter 314.
[0036]
The control means 31 includes an auto power off timer in order to suppress wasteful power consumption.
[0037]
The auto power off timer automatically turns off the power after a predetermined time (for example, 60 seconds) from the start of the timer when the power switch 3 is left on. Even when the power switch 3 is turned off within a predetermined time from the start of the auto power off timer, the timer continues its counting operation (time measurement) until the predetermined time elapses.
[0038]
As shown in FIG. 5, the infrared sensor 101 includes a thermopile (thermocouple array) 102. The hot contact 103 of the thermopile 102 is installed in the heat collecting portion 106 located on the center side via the thermal insulation band 105, and the cold junction 104 is installed on the outer peripheral side of the thermal insulation band 105.
[0039]
A temperature sensor 107 is installed in the vicinity of the infrared sensor 101. The temperature sensor 107 detects the temperature on the outer peripheral side of the thermal insulation band 105 of the infrared sensor 101, that is, the temperature of the cold junction 104, and also detects the temperature of the atmosphere (environment temperature). As the temperature sensor 107, a sensor that measures temperature with a resistor is used. For example, a thermistor can be used as a sensor for measuring temperature with a resistor.
[0040]
In such a temperature detection unit 10, a signal corresponding to a temperature difference between the hot junction 103 heated by infrared irradiation and the cold junction 104 not irradiated with infrared rays by the infrared sensor 101 and the temperature sensor 107, and the vicinity of the cold junction 104. The body temperature can be measured by detecting a signal corresponding to the temperature (environment temperature).
[0041]
Next, the usage method, circuit configuration, and operation of the thermometer 1 will be described.
As described above, the probe 6 is screwed and attached to the small diameter portion 72 of the support base 7 of the thermometer main body 2, and the probe cover 11 is put on the probe 6. Next, from above, the ring nut 9 is inserted and screwed into the large diameter portion 71 of the support base 7. As a result, the body 12 of the probe cover 11 is sandwiched between the inclined portion 64 of the probe 6 and the engaging portion 93 of the ring nut 9, and the probe cover 11 is fixed to the probe 6. Thereby, the mounting of the probe cover 11 is completed.
[0042]
Next, the power switch 3 is turned on, and after a predetermined time has passed, the thermometer body 2 is gripped, and the probe 6 encapsulated by the probe cover 11 is inserted into the ear cavity.
[0043]
Next, the measurement switch 4 is pressed for a predetermined time. Thereby, the body temperature is measured. That is, infrared rays (heat rays) radiated from the ear (tympanic membrane) are sequentially transmitted through the membrane 14 and the protective sheet 81, introduced into the light guide 8, and repeatedly reflected on the inner surface of the infrared sensor 101 of the temperature measuring unit 10. And the heat collecting unit 106 is irradiated.
[0044]
As shown in FIG. 6, the infrared sensor 101 obtains an output signal (TP signal) from the hot junction 103 as a positive output terminal and an output signal (VREF signal) from the cold junction 104 as a negative output terminal.
[0045]
The level (voltage) of the VREF signal from the cold junction 104 of the infrared sensor 101 is constant (fixed) regardless of the environmental temperature.
[0046]
The amplifying unit 32 includes a first amplifier 33 and a second amplifier 34 connected to the output side of the first amplifier 33. Each of the first amplifier 33 and the second amplifier 34 is a differential amplifier.
[0047]
The TP signal output from the infrared sensor 101 is amplified by the first amplifier 33 and input to the second amplifier 34. The first amplifier 33 removes unnecessary frequency band components included in the TP signal and the VREF signal as necessary.
[0048]
Further, the VREF signal output from the infrared sensor 101 is input to the first amplifier 33 and the second amplifier 34. The second amplifier 34 also removes unnecessary frequency band components included in a TP ″ signal and a VREF signal, which will be described later, as necessary.
[0049]
In the first amplifier 33, the difference between the TP signal and the VREF signal is amplified, and a signal TP ″ signal obtained by adding the VREF signal is obtained. Further, in the second amplifier 34, the difference between the TP ″ signal and the VREF signal is obtained. Are amplified, and the VREF signal is added and output as a TP ′ signal. The level of this TP ′ signal corresponds to the temperature difference between the hot junction 103 and the cold junction 104. Unless otherwise specified, the signal from the infrared sensor means the TP ′ signal.
[0050]
When the changeover switch 35 is switched to the TP ′ signal side, the TP ′ signal is input to the comparator 37, and when the changeover switch 35 is switched to the VREF signal side, the VREF signal from the first amplifier 33 is input to the comparator 37. . The driving of the changeover switch 35 is controlled by the control means 31.
[0051]
The VREF signal from the first amplifier 33 is also an infrared detection standardized signal that standardizes the TP ′ signal. By standardizing the TP ′ signal with this VREF signal (strictly speaking, Ttp is standardized with Tvref, which will be described later), for example, it is possible to reduce (cancel) the influence of circuit stray capacitance and chip component variations. This improves the measurement accuracy. The cold junction 104 and the first amplifier 33 constitute infrared detection standardized signal generation means.
[0052]
A constant (fixed) level reference voltage is applied to the integrating circuit 36. The integration circuit 36 generates a reference signal based on the reference voltage, and the reference signal is input to the comparator 37. The reference voltage is set sufficiently higher than the level of the TP ′ signal and the level of the VREF signal.
[0053]
When detecting the TP ′ signal, the changeover switch 35 is switched to the TP ′ signal side by the control signal from the control means 31. Then, an STC signal (sampling start signal) is transmitted from the control means 31 to the integrating circuit 36.
[0054]
As shown in FIG. 7, when receiving the STC signal, the integration circuit 36 decreases (drops) the level of the reference signal from the reference voltage with a constant gradient (slope).
[0055]
As shown in FIG. 6, the comparator 37 compares the level of the reference signal with the level of the TP ′ signal. When the level of the reference signal matches the level of the TP ′ signal, the comparator 31 sends an EOC signal (sampling end). Signal) and a trigger signal to the integrating circuit 36.
[0056]
As shown in FIG. 7, when the integration circuit 36 receives the trigger signal, the level of the reference signal is instantaneously restored to the original level, that is, the reference voltage.
[0057]
In the control unit 31, the timer 313 measures the time (Ttp) from when the STC signal is transmitted to when the EOC signal is received. This time information, that is, Ttp is stored in the memory 312.
[0058]
The level of the TP ′ signal changes according to the temperature difference between the hot junction 103 and the cold junction 104, and Ttp also changes accordingly. In this case, as the temperature difference between the hot junction 103 and the cold junction 104 is larger, the level of the TP ′ signal is larger and Ttp is shorter (smaller).
[0059]
The integration circuit 36 and the comparator 37 constitute a conversion means for converting the level of the TP ′ signal and the level of the VREF signal described later into time.
[0060]
As shown in FIG. 6, when the VREF signal is detected (when the signal from the infrared detection standardized signal generating means is detected), the changeover switch 35 is switched to the VREF signal side by the control signal from the control means 31. . Then, the STC signal is transmitted from the control means 31 to the integrating circuit 36.
[0061]
As shown in FIG. 7, when receiving the STC signal, the integrating circuit 36 decreases the level of the reference signal from the reference voltage with a constant gradient.
[0062]
As shown in FIG. 6, the comparator 37 compares the level of the reference signal with the level of the VREF signal. When the level of the reference signal matches the level of the VREF signal, the comparator 37 transmits an EOC signal to the control means 31. A trigger signal is transmitted to the integrating circuit 36.
[0063]
As shown in FIG. 7, when the integration circuit 36 receives the trigger signal, the level of the reference signal is instantaneously restored to the original level, that is, the reference voltage.
[0064]
In the control unit 31, the timer 313 measures the time (Tvref) from when the STC signal is transmitted to when the EOC signal is received. This time information, that is, Tvref is stored in the memory 312.
[0065]
As shown in FIG. 6, the relay circuit 41 includes a capacitor (not shown) and the like, and constitutes a part of an oscillation circuit (CR oscillation circuit).
[0066]
When the changeover switch 39 is switched to the temperature sensor 107 side, the relay circuit 41 and the temperature sensor 107 form an oscillation circuit. When the changeover switch 39 is switched to the reference resistor 38 side, the relay circuit 41 and the reference resistor 38 are connected to the oscillation circuit. Is configured. The driving of the changeover switch 39 is controlled by the control means 31.
[0067]
Although the resistance value TH of the temperature sensor 107 changes according to the environmental temperature, the resistance value RH of the reference resistor 38 is constant (fixed) regardless of the environmental temperature.
[0068]
When the resistance value TH of the temperature sensor 107 is detected (when a signal from the temperature sensor 107 is detected), the changeover switch 39 is switched to the temperature sensor 107 side by a control signal from the control means 31.
[0069]
Thus, the relay circuit 41 and the temperature sensor 107 constitute an oscillation circuit, and oscillation is generated by this oscillation circuit. The signal (oscillation signal) at that time, that is, the Fth signal is output from the relay circuit 41 and input to the control means 31.
[0070]
As shown in FIG. 8, in the control means 31, the counter 314 counts the number of pulses of the input Fth signal, and the timer 313 requires the counter 314 to count a predetermined number (for example, 256) of pulses. Time (Tth), that is, time (Tth) that is an integral multiple (for example, 256 times) of the period (wavelength) of the Fth signal is measured. This time information, that is, Tth is stored in the memory 312.
[0071]
The resistance value TH of the temperature sensor 107 changes according to the environmental temperature, and Tth also changes accordingly. In this case, the resistance value TH of the temperature sensor 107 increases as the environmental temperature decreases. In the CR oscillation circuit, since the period (wavelength) of the oscillation signal is proportional to the resistance value, the lower the environmental temperature, the longer the period of the Fth signal and the longer (large) Tth.
[0072]
As shown in FIG. 6, when the resistance value RH of the reference resistor 38 is detected (when the temperature detection standardization signal is detected), the changeover switch 39 is moved to the reference resistor 38 side by the control signal from the control means 31. Switch.
[0073]
Thus, the relay circuit 41 and the reference resistor 38 constitute an oscillation circuit, and oscillation is generated by this oscillation circuit. The signal (oscillation signal) at that time, that is, the Frh signal is output from the relay circuit 41 and input to the control means 31.
[0074]
The Frh signal is a temperature detection normalization signal that normalizes the Fth signal. By normalizing the Fth signal with this Frh signal (strictly speaking, Tth is standardized with Trh, which will be described later), for example, it is possible to reduce (cancel) the influence of circuit stray capacitance and chip component variations. This improves the measurement accuracy. The reference resistor 38 and the relay circuit 41 constitute a temperature detection standardized signal generating unit.
[0075]
As shown in FIG. 8, in the control means 31, the counter 314 counts the number of pulses of the input Frh signal, and the timer 313 requires the counter 314 to count a predetermined number (for example, 256) of pulses. Time (Trh), that is, a time (Trh) that is an integral multiple (for example, 256 times) of the period (wavelength) of the Frh signal is measured. This time information, that is, Trh is stored in the memory 312.
[0076]
Since the resistance value RH of the reference resistor 38 is constant regardless of the environmental temperature, the period of the Frh signal is constant, and therefore Trh is constant.
[0077]
The calculation unit 311 of the control unit 31 reads Ttp, Tvref, Tth, and Trh from the memory 312, normalizes Ttp with Tvref, and normalizes Tth with Trh. That is, Ttp / Tvref and Tth / Trh are obtained, respectively.
[0078]
Then, based on these Ttp / Tvref and Tth / Trh, a predetermined calculation process is performed, and a predetermined temperature correction is performed as necessary to determine the temperature of the measurement site (heat source), that is, the body temperature.
[0079]
The obtained body temperature is displayed on the display unit 5. Further, when the measurement of the body temperature is completed, the buzzer 42 sounds to notify it. The operator pulls out the probe 6 from the ear cavity by the notification of the buzzer 42.
[0080]
In this thermometer 1, in the measurement of the body temperature, the above-described detection of the TP ′ signal (detection of the signal from the infrared sensor 101), that is, measurement of Ttp (measurement), detection of the VREF signal, that is, measurement of Tvref, and Fth signal Detection (detection of signal from the temperature sensor 107), that is, measurement of Tth and detection of Frh signal, that is, measurement of Trh are performed in a predetermined order (performed in a time-sharing manner).
[0081]
In this case, the detection times of the TP ′ signal, the VREF signal, the Fth signal and the Frh signal are correlated (substantially coincident) with Ttp, Tvref, Tth and Trh, respectively. Then, the larger the temperature difference between the hot junction 103 and the cold junction 104, the shorter the detection time of the TP ′ signal, and the lower the environmental temperature, the longer the detection time of the Fth signal signal. The detection time of the VREF signal and the detection time of the Frh signal are constant regardless of the environmental temperature and the temperature difference between the hot junction 103 and the cold junction 104, respectively.
[0082]
Here, the temperature (body temperature) of the measurement site is about 37 ± 2 ° C. even if it fluctuates, but the environmental temperature varies within a range of about 0 to 35 ° C., for example. For this reason, most of the causes of variations in the detection time of the TP ′ signal are due to variations in environmental temperature rather than body temperature.
[0083]
Further, the body temperature is about 37 ± 2 ° C. and the environmental temperature is about 0 to 35 ° C. Therefore, the lower the environmental temperature, the larger the temperature difference between the body temperature and the environmental temperature. The temperature difference with the contact 104 is large.
[0084]
The above relationship is shown in FIG. The graph shown in FIG. 9 schematically shows the relationship between the detection time of the TP ′ signal and the Fth signal when measuring the body temperature in the thermometer 1, the environmental temperature, and the temperature difference between the body temperature and the environmental temperature.
[0085]
As shown in FIG. 9, in this thermometer 1, the lower the ambient temperature, that is, the greater the temperature difference between the body temperature and the ambient temperature (the greater the temperature difference between the hot junction 103 and the cold junction 104), the more the TP ′ signal. The detection time is short. The detection time of the Fth signal is longer as the environmental temperature is lower.
[0086]
That is, the thermometer 1 is configured such that the characteristic due to the temperature change of the TP ′ signal detection time and the characteristic due to the temperature change of the Fth signal detection time are reversed. In other words, the shorter the detection time of the TP ′ signal, the longer the detection time of the Fth signal (the long / short relationship is reversed).
[0087]
Therefore, the total time of the detection time of the TP ′ signal and the detection time of the Fth signal approaches a constant value.
[0088]
In this case, it is preferable to set various conditions such as circuit constants so that the total time of the detection time of the TP ′ signal and the detection time of the Fth signal is as constant as possible.
[0089]
As described above, according to the thermometer 1, it is possible to reduce the fluctuation of the measurement time of the body temperature due to the fluctuation of the environmental temperature. Thereby, an erroneous operation is prevented.
[0090]
The thermometer 1 further has the following advantages.
For detection of the Fth signal and the Frh signal, as shown in FIG. 11, the number of pulses input within a certain time, that is, the period (counting period) from the rising edge 52 to the falling edge 53 of the gate signal 51 is counted. There is also a method using the number of pulses (detection time = constant), but in this method, for example, for the signals A and B having slightly different periods, the number of pulses is 4, and an error of Δt occurs in four periods. . In order to reduce the influence of this error, the width of the gate signal 51, that is, the counting period may be lengthened. However, if the counting period is lengthened, the measurement time of the body temperature increases.
[0091]
On the other hand, as described above, the thermometer 1 counts the number of input pulses and measures the time required to count a predetermined number of pulses. Therefore, the Tth and Trh can be accurately measured without increasing the measurement time. Can be measured. That is, the measurement accuracy of body temperature can be improved without increasing the measurement time.
[0092]
As mentioned above, although the thermometer of this invention was demonstrated based on the Example shown to an accompanying drawing, this invention is not limited to this, The structure of each part is substituted by the thing of the arbitrary structures which have the same function. be able to.
[0093]
For example, in the present invention, as shown in FIG. 10, the lower the environmental temperature, that is, the greater the temperature difference between the temperature of the measurement site (body temperature) and the environmental temperature (the temperature difference between the hot junction 103 and the cold junction 104 is smaller). The detection time of the TP ′ signal (signal from the infrared sensor) is longer and the detection time of the Fth signal (signal from the temperature sensor) is shorter as the environmental temperature is lower. Good.
[0094]
Also in this case, like the thermometer 1 described above, the total time of the detection time of the TP ′ signal and the detection time of the Fth signal approaches a constant value, and the fluctuation of the measurement time of the body temperature due to the fluctuation of the environmental temperature can be reduced. .
[0095]
Moreover, although the said Example is an ear-type thermometer, if this invention detects the intensity | strength of the infrared rays emitted from a measurement site | part and is a thermometer which measures body temperature, it is not limited to an ear-type thermometer.
The present invention can also be applied to a general thermometer that is not a thermometer.
[0096]
【The invention's effect】
As described above, according to the infrared thermometer of the present invention, fluctuations in body temperature measurement time due to fluctuations in environmental temperature can be reduced. Thereby, an erroneous operation is prevented.
[0097]
In addition, when measuring the time that is an integral multiple of the period of the signal output from the oscillation circuit and obtaining the body temperature using the time information, the measurement accuracy is reduced while shortening the body temperature measurement time. Can be improved.
[Brief description of the drawings]
FIG. 1 is a front view of a thermometer according to the present invention.
FIG. 2 is a side view of the thermometer of the present invention.
FIG. 3 is a cross-sectional view taken along line AA in FIG. 1 showing a state in which the probe cover is attached to the probe in the thermometer of the present invention.
FIG. 4 is a cross-sectional side view schematically showing the internal structure of the thermometer of the present invention.
FIG. 5 is a perspective view showing a configuration example of a temperature detector in the thermometer of the present invention.
FIG. 6 is a block diagram showing a circuit configuration example of the thermometer of the present invention.
FIG. 7 is a timing chart showing a reference signal and a TP ′ signal or a VREF signal in the present invention.
FIG. 8 is a timing chart showing an Fth signal or an Frh signal in the present invention.
FIG. 9 is a graph schematically showing the relationship between the detection time of the TP ′ signal and the Fth signal, the environmental temperature, and the temperature difference between the body temperature and the environmental temperature when measuring the body temperature in the present invention.
FIG. 10 is a graph schematically showing the relationship between the detection time of the TP ′ signal and the Fth signal, the environmental temperature, and the temperature difference between the body temperature and the environmental temperature when measuring the body temperature in the present invention.
FIG. 11 is a timing chart showing a gate signal, a signal A, and a signal B.
[Explanation of symbols]
1 Thermometer
2 Thermometer body
21 Casing
3 Power switch
4 Measurement switch
5 display section
6 Probe
61 Base
62 Male Screw
63 Tip outer periphery
64 slope
7 Support stand
71 Large diameter part
72 Small diameter part
73, 74 Male screw
8 Light guide
81 Protective sheet
9 Ring nut
91 female screw
92 Tapered part
93 engaging part
94 Tip
95 groove
10 Temperature detector
101 Infrared sensor
102 Thermopile (thermocouple array)
103 Hot junction
104 Cold junction
105 Thermal insulation band
106 Heat collector
107 temperature sensor
11 Probe cover
12 Torso
14 Membrane
15 Lip part
30 Circuit board
31 Control means
311 Calculation unit
312 memory
313 timer
314 counter
32 Amplification means
33 First amplifier
34 Second amplifier
35 selector switch
36 Integration circuit
37 comparator
38 Reference resistance
39 changeover switch
40 Power supply
41 Relay circuit
42 Buzzer
51 Gate signal
52 Rise
53 Falling

Claims (2)

Equipped with a resistor whose resistance value increases as the temperature decreases, the greater the temperature difference between the temperature sensor that detects the ambient temperature and the hot and cold junctions, the greater the level of the signal that is output. An infrared sensor that detects the intensity of infrared rays emitted, and an infrared thermometer that measures body temperature based on signals from the temperature sensor and the infrared sensor;
A CR oscillation circuit including a resistor of the temperature sensor as a resistor; And detecting the signal from the infrared sensor, the level of the reference signal is decreased from a predetermined value larger than the level of the signal from the infrared sensor, and the reference signal By measuring the time until the level matches the level of the signal from the infrared sensor and obtaining the second time information corresponding to the intensity of infrared rays emitted from the measurement site, the environmental temperature is low As the detection time of the signal from the temperature sensor is longer and the temperature difference between the temperature of the measurement site and the ambient temperature is larger, the infrared sensor Detection time of a signal from the over is configured to be shorter,
An infrared thermometer characterized in that a body temperature is obtained using the first time information and the second time information. The infrared thermometer according to claim 1, wherein a total time of a detection time of the signal from the temperature sensor and a detection time of the signal from the infrared sensor is constant.

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